Apparatus for twisting synthetic yarn to impart stretch and softness



Oct. 29, 1968 H RADECKI ETAL 3,407,584

APPARATUS FOR TwIsTING SYNTHETIC YARN To IMPART STRETCH soFTNEss Filed July 1966 NVENTORS HUBER-r QAoeem WLAovsLAwGuNoLncH ATTO RNEYS United States Patent O 3 Claims. (ci. 57-3/4) ABSTRACT OF THE DISCLOSURE A method and apparatus for twisting synthetic yarn to impart stretch and softness, which includes subjecting yarn passing linearly through a chamber to the action of a whirling air stream. The apparatus consists of an enl closure having air passages of helical contour of downwardly diminshing radii. The passages open at the bottom to a chamber through which yarn is drawn axially of the passage convolutions.

The invention relates to a device for curling yarn from synthetic fibre by means of compressed air.

For the production of such knitted articles as elastic socks, stockings and linen or clothing use is made of yarn of synthetic fibres, mostly polyamide or polyacrylonitride fibres which have been made downy and elastic.

A commonly used method of making this yarn is the false twist curling method.

Until now the yarn curling was performed so that a feeding roller directed the yarn to a heater, and, after treating, the yarn passed a spindle, winding itself at its outlet round a pin placed vertically to the spindle centre line.

The spindle, rotating with high speed, driven mechanically and supported on ball bearings, reached thousands of revolutions per minute. The spindle twisted the part of yarn fed by the roller to the spindle in one way and the part from the spindle to the receiving roller was twisted in the other way. The yarn was continuously fed. As a result of this the yarn twisted before reaching the spindle was untwisted after leaving the spindle. The yarn however, after leaving the spindle had a small twist. This fact was caused by the following circumstances: different distances between the feeding roller and spindle, the spindle and receiving roller, different number of twists before reaching and after leaving the spindle increased temperature of yarn on the part ahead of the spindle and the preexistence of a small twist on the delivered yarn to be curled.

All these parameters are interrelated and that is why a small twist is left on the yarn after leaving the spindle.

An additional point should be taken into consideration, forming a twist on the yarn before reaching the spindle at the momentary plasticity of twist, which, after leaving the spindle, remained in the shape of an elongated spiral consisting of different twisted libres. Such a yarn was received by the receiving device and wound on a cylindrical coil.

The increased demand for products from curled yarn entailed the necessity of increasing the output of devices producing that type of yarn.

Known twisting devices have now reached the limit of technical speed possibilities of revolutions, amounting sometimes to two hundred thousand per minute. The application of devices with very high speed increases their output but causes, at the same time, very rapid wear of their basic elements which must be frequently replaced. The rotating elements are very diflicult to manufacture, because they require the highest machining skill as well as dynamic balancing.

When using these devices, the curled yarn obtained was of'lower quality. The yarn bres overheated in the heater, and possessing then excessive plasticity, and being stretched while passing through the pin in the spindle became fused. As a result of this, the number of libres in the yarn was reduced. Such a yarn did not correspond to the requirements of the technical parameters.

These defects of yarn can be avoided and a simultaneous increase of its production obtained by curling it by means of compressed air.

After heating in a traditional heating device, the yarn from synthetic fibre, preferably from polyamide or po lyacrylonitrite fllbresyis fed with constant speed through a narrow channel. When the yarn leaves the channel, it is subjected to a stream of compressed air, which should be narrow, whirled and of great force and speed. The air flows round the yarn and transfers its whirl torque to it, twisting it with a speed amounting to ninety thousand revolutions per minute. Afterwards, the yarn passing through the known receiving devices is wound on a cylindrical coil.

An example of the invention is shown in the drawing. FIG. 1 represents a vertical cross-section of the device, FIG. 2 is a cross-section of the device taken on the line AA of FIG. 1.

In the body 1, made of any material and of hollow conical shape, there is placed a matched frusto-cone 2, made of metal or plastic, and having a flat top 3. The cone 2 has helical flutes 4 which run from its base 5 to its top 3. On body 1 there is fixed a cover 6 with a seal 7. Extending through cover 6, seal 7 and cone 2 there is a channel 8 opening into a chamber 9 within the body below the top 3. The seal 7 separates the channel 8 from an equalising chamber 10, located within the body 1, above cone 2 and closed by cover 6. The cover 6 is provided With an inlet stub 11 for supplying compressed air.

The yarn to be curled is passed through known feeding and heating devices and pulled through the longitudinal channel 8, and afterwards it is connected to known receiving devices. After starting up the feeding and receiving devices, compressed air, of a pressure of about 3 lig/sq. cm. is let into the stub 11. The air flows through stub 11, equalising chamber 10 and into the helical flutes 4. As the radius of cone 2 reduces downwards, the whirl radius is also decreased. The compressed air let into the stub 11 and flowing through flutes 4 is subjected to the whirl radius. In the whirl chamber 9, the air coming from the flutes 4 transmits its energy to the yarn causing it to rotate.

During its travel, the yarn passing outside the device is being untwisted. The twists, however, on the individual fibers at the momentary plasticity of the yarn beyond untwisting after the spindle, changed into spiral turns since the whirling air acted on the yarn not only as to twist it but also to stretch it. The yarn is not only elastic but also downy.

Then the curled yarn is wound on a coil by means of a conventional receiving device.

The rotational speed of the yarn may be from a few revolutions to a few thousand revolutions per minute. It depends on the air pressure, cone angle, helical flute line angles, whirl chamber size and diameter of the channel running through the centre of the device.

The yarn curled according to the present invention is elastic and downy, without fused fibres, and is increased in quality and sort.

The device of the invention is characterized by easy operation, consisting in setting the rotational speed of yarn by the control of the pressure of the input air. The individual components of the device are simple and cheap to produce, durable and are subject to no wear. The device entirely eliminates the noise caused by the operation of a twisting spindle. Additionally, use of the device diminishes the size of the twisting machine, thus enabling the production area to be used for other devices.

We claim:

1. A device for curling synthetic yarn comprising, a body having a closed conical chamber therein, a center plug of frusto-conical shape seated in the chamber whereby a small whirling chamber is formed in the tip of the body chamber, a yarn passage opening through the housing and plug centrally of the conical chamber with said whirling chamber forming part of said yarn passage, helical grooves formed in the outer conical walls of the plug forming with the surrounding conical chamber wall helica air passages open at one end to the whiring chamber, and means carried by the housing to conduct air under pressure to the other ends of the air passages.

2. A device as claimed in claim 1 wherein, the center plug is of less depth than the conical chamber forming an equalizing chamber within the housing separated from the whirling chamber by the plug, a tubular seal traversing the equalizing chamber forming part of the yarn passage, the said other ends of the air passages opening to the equalizing chamber, and the equalizing chamber forming part of the means to conduct air to the air passages.

3. A device as claimed in claim 1 wherein, the air passages extend the full depth of the center plug, an equalizing chamber within the conical chamber separated from the whirling chamber by the depth of center plug and into which the air passages open, the equalizing chamber forming part of the means to conduct air to the air passages.

References Cited UNITED STATES PATENTS 2,783,609 3/1957 Breen 57-34 2,990,671 7/1961 Bunting et al. 57-34 3,116,588 1/1964 Breen et al. 28-72 XR 3,217,482 11/1965 Baer 57--34 XR 3,279,024 10/1966 Sakai et al 57-34 XR FRANK J. COHEN, Primary Examiner.

DONALD E. WATKINS, Assistant Examiner. 

